Influence of static stress on damping behavior in Fe–15Cr and Fe–8Al ferromagnetic alloys

Abstract

Effect of static stress on magnetomechanical damping of Fe–15Cr and Fe–8Al (wt.%) alloys has been investigated by using dynamic mechanical analyzer (DMA) with three-point bending model. The temperature sweeping is used to measure the damping capacity and the variation of damping capacity with strain amplitude under different static stresses is deduced through a matrix method. The result shows that three-point bending model is capable for measuring magnetomechanical damping capacity with reliable results. Under no static stress condition, the deduced damping curve is fitted well with Smith and Birchak (S–B) model at low strain amplitude. However, the deduced damping capacity is higher than the value predicted by S–B model at high strain amplitude. With increasing static stress, the deduced damping capacity decreases significantly and becomes strain amplitude-independent. Compared with S–B model, the deduced damping capacity under applied stress is obviously higher which can be associated with the dislocation damping generated by unpinning dislocations as the static stress increases.